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popen.c revision 1.10 
      1 /*	$NetBSD: popen.c,v 1.10 2002/03/02 14:59:37 wiz Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1980, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #ifndef lint
     38 #if 0
     39 static char sccsid[] = "@(#)popen.c	8.1 (Berkeley) 6/6/93";
     40 #else
     41 __RCSID("$NetBSD: popen.c,v 1.10 2002/03/02 14:59:37 wiz Exp $");
     42 #endif
     43 #endif /* not lint */
     44 
     45 #include "rcv.h"
     46 #include "extern.h"
     47 
     48 #define READ 0
     49 #define WRITE 1
     50 
     51 struct fp {
     52 	FILE *fp;
     53 	int pipe;
     54 	int pid;
     55 	struct fp *link;
     56 };
     57 static struct fp *fp_head;
     58 
     59 struct child {
     60 	int pid;
     61 	char done;
     62 	char free;
     63 	int status;
     64 	struct child *link;
     65 };
     66 static struct child *child;
     67 static struct child *findchild(int);
     68 static void delchild(struct child *);
     69 static int file_pid(FILE *);
     70 
     71 FILE *
     72 Fopen(char *file, char *mode)
     73 {
     74 	FILE *fp;
     75 
     76 	if ((fp = fopen(file, mode)) != NULL) {
     77 		register_file(fp, 0, 0);
     78 		(void) fcntl(fileno(fp), F_SETFD, 1);
     79 	}
     80 	return fp;
     81 }
     82 
     83 FILE *
     84 Fdopen(int fd, char *mode)
     85 {
     86 	FILE *fp;
     87 
     88 	if ((fp = fdopen(fd, mode)) != NULL) {
     89 		register_file(fp, 0, 0);
     90 		(void) fcntl(fileno(fp), F_SETFD, 1);
     91 	}
     92 	return fp;
     93 }
     94 
     95 int
     96 Fclose(FILE *fp)
     97 {
     98 	unregister_file(fp);
     99 	return fclose(fp);
    100 }
    101 
    102 FILE *
    103 Popen(char *cmd, char *mode)
    104 {
    105 	int p[2];
    106 	int myside, hisside, fd0, fd1;
    107 	int pid;
    108 	sigset_t nset;
    109 	FILE *fp;
    110 
    111 	if (pipe(p) < 0)
    112 		return NULL;
    113 	(void) fcntl(p[READ], F_SETFD, 1);
    114 	(void) fcntl(p[WRITE], F_SETFD, 1);
    115 	if (*mode == 'r') {
    116 		myside = p[READ];
    117 		fd0 = -1;
    118 		hisside = fd1 = p[WRITE];
    119 	} else {
    120 		myside = p[WRITE];
    121 		hisside = fd0 = p[READ];
    122 		fd1 = -1;
    123 	}
    124 	sigemptyset(&nset);
    125 	if ((pid = start_command(cmd, &nset, fd0, fd1, NOSTR, NOSTR, NOSTR)) < 0) {
    126 		close(p[READ]);
    127 		close(p[WRITE]);
    128 		return NULL;
    129 	}
    130 	(void) close(hisside);
    131 	if ((fp = fdopen(myside, mode)) != NULL)
    132 		register_file(fp, 1, pid);
    133 	return fp;
    134 }
    135 
    136 int
    137 Pclose(FILE *ptr)
    138 {
    139 	int i;
    140 	sigset_t nset, oset;
    141 
    142 	i = file_pid(ptr);
    143 	unregister_file(ptr);
    144 	(void) fclose(ptr);
    145 	sigemptyset(&nset);
    146 	sigaddset(&nset, SIGINT);
    147 	sigaddset(&nset, SIGHUP);
    148 	sigprocmask(SIG_BLOCK, &nset, &oset);
    149 	i = wait_child(i);
    150 	sigprocmask(SIG_SETMASK, &oset, NULL);
    151 	return i;
    152 }
    153 
    154 void
    155 close_all_files(void)
    156 {
    157 
    158 	while (fp_head)
    159 		if (fp_head->pipe)
    160 			(void) Pclose(fp_head->fp);
    161 		else
    162 			(void) Fclose(fp_head->fp);
    163 }
    164 
    165 void
    166 register_file(FILE *fp, int pipe, int pid)
    167 {
    168 	struct fp *fpp;
    169 
    170 	if ((fpp = (struct fp *) malloc(sizeof *fpp)) == NULL)
    171 		errx(1, "Out of memory");
    172 	fpp->fp = fp;
    173 	fpp->pipe = pipe;
    174 	fpp->pid = pid;
    175 	fpp->link = fp_head;
    176 	fp_head = fpp;
    177 }
    178 
    179 void
    180 unregister_file(FILE *fp)
    181 {
    182 	struct fp **pp, *p;
    183 
    184 	for (pp = &fp_head; (p = *pp) != NULL; pp = &p->link)
    185 		if (p->fp == fp) {
    186 			*pp = p->link;
    187 			free((char *) p);
    188 			return;
    189 		}
    190 	errx(1, "Invalid file pointer");
    191 }
    192 
    193 static int
    194 file_pid(FILE *fp)
    195 {
    196 	struct fp *p;
    197 
    198 	for (p = fp_head; p; p = p->link)
    199 		if (p->fp == fp)
    200 			return (p->pid);
    201 	errx(1, "Invalid file pointer");
    202 	/*NOTREACHED*/
    203 }
    204 
    205 /*
    206  * Run a command without a shell, with optional arguments and splicing
    207  * of stdin and stdout.  The command name can be a sequence of words.
    208  * Signals must be handled by the caller.
    209  * "Mask" contains the signals to ignore in the new process.
    210  * SIGINT is enabled unless it's in the mask.
    211  */
    212 /*VARARGS4*/
    213 int
    214 run_command(char *cmd, sigset_t *mask, int infd, int outfd, char *a0,
    215 	    char *a1, char *a2)
    216 {
    217 	int pid;
    218 
    219 	if ((pid = start_command(cmd, mask, infd, outfd, a0, a1, a2)) < 0)
    220 		return -1;
    221 	return wait_command(pid);
    222 }
    223 
    224 /*VARARGS4*/
    225 int
    226 start_command(char *cmd, sigset_t *mask, int infd, int outfd,
    227 	      char *a0, char *a1, char *a2)
    228 {
    229 	int pid;
    230 
    231 	if ((pid = vfork()) < 0) {
    232 		perror("fork");
    233 		return -1;
    234 	}
    235 	if (pid == 0) {
    236 		char *argv[100];
    237 		int i = getrawlist(cmd, argv, sizeof argv / sizeof *argv);
    238 
    239 		if ((argv[i++] = a0) != NOSTR &&
    240 		    (argv[i++] = a1) != NOSTR &&
    241 		    (argv[i++] = a2) != NOSTR)
    242 			argv[i] = NOSTR;
    243 		prepare_child(mask, infd, outfd);
    244 		execvp(argv[0], argv);
    245 		perror(argv[0]);
    246 		_exit(1);
    247 	}
    248 	return pid;
    249 }
    250 
    251 void
    252 prepare_child(sigset_t *nset, int infd, int outfd)
    253 {
    254 	int i;
    255 	sigset_t eset;
    256 
    257 	/*
    258 	 * All file descriptors other than 0, 1, and 2 are supposed to be
    259 	 * close-on-exec.
    260 	 */
    261 	if (infd >= 0)
    262 		dup2(infd, 0);
    263 	if (outfd >= 0)
    264 		dup2(outfd, 1);
    265 	for (i = 1; i < NSIG; i++)
    266 		if (nset != NULL && sigismember(nset, i))
    267 			(void) signal(i, SIG_IGN);
    268 	if (nset == NULL || !sigismember(nset, SIGINT))
    269 		(void) signal(SIGINT, SIG_DFL);
    270 	sigemptyset(&eset);
    271 	(void) sigprocmask(SIG_SETMASK, &eset, NULL);
    272 }
    273 
    274 int
    275 wait_command(int pid)
    276 {
    277 
    278 	if (wait_child(pid) < 0) {
    279 		printf("Fatal error in process.\n");
    280 		return -1;
    281 	}
    282 	return 0;
    283 }
    284 
    285 static struct child *
    286 findchild(int pid)
    287 {
    288 	struct child **cpp;
    289 
    290 	for (cpp = &child; *cpp != NULL && (*cpp)->pid != pid;
    291 	     cpp = &(*cpp)->link)
    292 			;
    293 	if (*cpp == NULL) {
    294 		*cpp = (struct child *) malloc(sizeof (struct child));
    295 		(*cpp)->pid = pid;
    296 		(*cpp)->done = (*cpp)->free = 0;
    297 		(*cpp)->link = NULL;
    298 	}
    299 	return *cpp;
    300 }
    301 
    302 static void
    303 delchild(struct child *cp)
    304 {
    305 	struct child **cpp;
    306 
    307 	for (cpp = &child; *cpp != cp; cpp = &(*cpp)->link)
    308 		;
    309 	*cpp = cp->link;
    310 	free((char *) cp);
    311 }
    312 
    313 void
    314 sigchild(int signo)
    315 {
    316 	int pid;
    317 	int status;
    318 	struct child *cp;
    319 
    320 	while ((pid = wait3(&status, WNOHANG, NULL)) > 0) {
    321 		cp = findchild(pid);
    322 		if (cp->free)
    323 			delchild(cp);
    324 		else {
    325 			cp->done = 1;
    326 			cp->status = status;
    327 		}
    328 	}
    329 }
    330 
    331 int wait_status;
    332 
    333 /*
    334  * Wait for a specific child to die.
    335  */
    336 int
    337 wait_child(int pid)
    338 {
    339 	sigset_t nset, oset;
    340 	struct child *cp = findchild(pid);
    341 	sigemptyset(&nset);
    342 	sigaddset(&nset, SIGCHLD);
    343 	sigprocmask(SIG_BLOCK, &nset, &oset);
    344 
    345 	while (!cp->done)
    346 		sigsuspend(&oset);
    347 	wait_status = cp->status;
    348 	delchild(cp);
    349 	sigprocmask(SIG_SETMASK, &oset, NULL);
    350 	return wait_status ? -1 : 0;
    351 }
    352 
    353 /*
    354  * Mark a child as don't care.
    355  */
    356 void
    357 free_child(int pid)
    358 {
    359 	sigset_t nset, oset;
    360 	struct child *cp = findchild(pid);
    361 	sigemptyset(&nset);
    362 	sigaddset(&nset, SIGCHLD);
    363 	sigprocmask(SIG_BLOCK, &nset, &oset);
    364 
    365 	if (cp->done)
    366 		delchild(cp);
    367 	else
    368 		cp->free = 1;
    369 	sigprocmask(SIG_SETMASK, &oset, NULL);
    370 }
    371